Which Protein Should I Stop Eating? A Guide to Identifying Unhealthy Protein Sources

October 26, 2025 •

5 min read

The World Health Organization (WHO) classifies processed meats like ham and bacon as a Group 1 carcinogen, meaning they are known to cause cancer. Given this, it's vital to know which protein should I stop eating or severely limit to protect your long-term health.

Quick Summary

Focus on cutting out or minimizing unhealthy protein sources, including processed meats, excessive fatty red meat, and low-quality protein powders. Replace these with lean, whole-food options to reduce health risks such as high cholesterol, cancer, and inflammation.

Key Points

Avoid Processed Meats: Heavily processed meats like bacon and hot dogs are classified as carcinogens and are high in sodium and saturated fat.
Limit Fatty Red Meat: High consumption of fatty red meat has been linked to increased risks of heart disease and stroke due to high saturated fat.
Be Wary of Protein Supplements: Low-quality protein powders can contain heavy metals, pesticides, and artificial additives. Check labels for added sugars and fillers.
Reduce Processed Dairy and Sugar: Minimize consumption of processed cheese slices and yogurts loaded with sugar, as they offer poor nutritional value.
Embrace Whole Food Proteins: Prioritize plant-based proteins, lean poultry, fish, and eggs for a balanced diet rich in essential nutrients and fiber.

Protein is a fundamental macronutrient, but not all protein sources are created equal. The accompanying nutrients—or additives—in a protein-rich food are what truly determine its health impact, making it crucial to understand the risks of certain options. For optimal health, a conscious effort should be made to reduce or completely eliminate specific protein types that contribute more harm than good.

Unhealthy Protein Sources to Cut Back On

Processed Meats

The most significant and well-documented unhealthy protein category is processed meat. These products, which include bacon, sausages, hot dogs, deli meats, and beef jerky, have been preserved through methods like salting, curing, fermenting, or smoking. The health risks are extensive and well-established by global health organizations.

Carcinogenic Compounds: The WHO classified processed meat as a Group 1 carcinogen, with strong evidence linking it to colorectal cancer and suggesting a link to stomach cancer. The nitrates and nitrites used as preservatives can form carcinogenic N-nitroso chemicals in the gut.
High Sodium Content: The preserving process involves high levels of sodium, a major contributor to high blood pressure, cardiovascular disease, and stroke.
Added Fats and Preservatives: These products are often high in saturated fat and can contain a range of other additives, providing little nutritional value for their caloric cost.

Fatty Red Meats

While unprocessed red meat is a valuable source of protein and nutrients like iron, certain types should be limited due to their high saturated fat content. Diets high in saturated fat can raise blood cholesterol and increase the risk of heart disease.

Higher Saturated Fat: Fattier cuts of beef, pork, and lamb contain higher levels of saturated fat compared to lean alternatives.
Increased Disease Risk: High consumption of red meat has been linked to a higher risk of heart disease and stroke.
Inflammatory Effects: Red meat consumption has been associated with increased inflammation, a driver of many chronic diseases.

Low-Quality Protein Powders

Protein supplements are not created equal, and many on the market should be approached with caution. Because they are classified as supplements, they are not regulated with the same scrutiny as food products.

Hidden Toxins: A 2022 report by the Clean Label Project revealed that some protein powders contained heavy metals (lead, arsenic, cadmium, mercury), BPA, pesticides, and other contaminants linked to health issues.
Added Sugars and Fillers: Many protein powders and bars are loaded with added sugars, artificial sweeteners, and fillers that can lead to blood sugar spikes and promote unhealthy gut bacteria.
Questionable Ingredients: The inclusion of artificial flavors, binders, and colors makes many commercially available options more like candy bars than nutritious supplements.

Processed Dairy and Sugary Yogurts

Not all dairy proteins are healthy choices. Certain processed versions are best minimized or avoided.

Processed Cheese: Often filled with processed oils and additives, manufactured cheese contains less protein and more sodium and unhealthy fats than its natural counterpart.
Sweetened Yogurts: While plain Greek yogurt is an excellent protein source, many flavored commercial yogurts are high in added sugar, negating their protein benefits.

Unhealthy vs. Healthy Protein Choices

To make a clear distinction, here is a comparison table outlining specific examples of proteins to limit or eliminate and their healthier replacements.


Protein to Limit or Avoid	Reason	Healthier Alternative	Benefit
Hot Dogs, Bacon, Salami	Carcinogens, high sodium, saturated fat, preservatives	Beans, Lentils, Tofu, Lean Poultry	Plant-based, lower in saturated fat, high in fiber
Fatty Cuts of Red Meat	High in saturated fat, linked to heart disease	Lean Cuts of Meat, Fish, Shellfish	Lower saturated fat, often rich in Omega-3s
Processed Cheese Slices	Additives, processed oils, high sodium	Natural Cheeses (in moderation), Cottage Cheese, Feta	Higher quality protein, fewer additives, less processed
Sugary Protein Bars	High in added sugars, artificial sweeteners, fillers	Greek Yogurt, Nuts, Seeds, Hard-Boiled Eggs	Whole food options, more nutrients, fewer additives
Mass Gainer Powders	High in added sugar, excessive calories, low-quality ingredients	High-Quality Protein Powder (check label), Whole Grains	Fewer additives, better ingredient quality, higher nutrient density

Making the Switch to Healthier Protein

Transitioning away from unhealthy proteins is a manageable process that involves mindful choices and simple swaps. The key is focusing on whole, unprocessed sources that provide beneficial nutrients alongside protein.

Prioritize Plant-Based Proteins: Beans, lentils, peas, nuts, seeds, and tofu are excellent, fiber-rich protein sources that are typically low in saturated fat. Incorporating these more frequently into your diet can significantly improve your overall health.
Opt for Lean Meats and Fish: When consuming animal protein, choose lean cuts of poultry (skinless chicken and turkey) and fish. Oily fish like salmon, sardines, and mackerel are especially beneficial due to their high omega-3 fatty acid content. Cook with healthier methods like baking, broiling, or grilling rather than frying.
Choose Better Dairy: Swap sugary yogurts for plain Greek or skyr yogurt. Select lower-fat, natural cheeses and consume them in moderation. Whole milk and full-fat dairy contain more saturated fat, so low-fat or skim options are often better.
Scrutinize Supplements: If you use protein powders, research brands and choose those with minimal, clean ingredients. Look for products without added sugars, artificial sweeteners, or preservatives. The Clean Label Project provides a useful resource for finding safer options.
Focus on the Protein "Package": Remember that the entire nutrient profile matters. A sirloin steak offers protein but also saturated fat, while lentils offer protein, fiber, and virtually no saturated fat. Evaluating the whole package helps make better dietary decisions.

Conclusion

Making informed choices about your protein intake is one of the most effective steps you can take for your long-term health. The question, "Which protein should I stop eating?" often leads to identifying processed meats, fatty red meats, low-quality protein supplements, and processed dairy as the primary culprits. By consciously reducing your intake of these items and prioritizing a variety of whole, unprocessed protein sources—both from plants and lean animal options—you can lower your risk of chronic disease and improve your overall well-being. A balanced, varied diet built on quality protein is the foundation for a healthier future. For further reading on healthy protein sources, consult the Harvard T.H. Chan School of Public Health's guide.

Frequently Asked Questions

Processed meats are classified by the WHO as a Group 1 carcinogen due to the formation of carcinogenic N-nitroso chemicals from preservatives like nitrates and nitrites. They are also high in sodium and saturated fat, which contribute to heart disease and high blood pressure.

You don't necessarily have to stop eating all red meat, but it's wise to limit fatty cuts and minimize consumption. When you do eat it, choose lean, unprocessed options. The health risks are linked to high consumption, so a small amount is less concerning than a meat-heavy diet.

A report by the Clean Label Project found some protein powders contain heavy metals, BPA, and pesticides. Many are also high in added sugars, artificial sweeteners, and fillers that can negatively impact gut health and blood sugar levels.

No, not all dairy is unhealthy. The issue lies primarily with highly processed dairy products like processed cheese and sugary yogurts, which contain high levels of saturated fat, sodium, and sugar. Healthier options include plain Greek yogurt, cottage cheese, and low-fat milk.

Excellent plant-based protein sources include legumes (beans, lentils, peas), nuts and seeds, and soy products like tofu and tempeh. These are typically rich in fiber and low in saturated fat.

You can replace unhealthy proteins by using healthier alternatives and flavorful cooking methods. Substitute plant-based proteins in burritos, soups, and stir-fries. For meat, opt for lean cuts and season with salt-free herbs and spices, then bake or grill instead of frying.

According to the Cancer Council NSW, it is best to cut out processed meats altogether or keep them to an absolute minimum to reduce cancer risk. There is evidence suggesting even small, daily portions can increase risk.